Biomedical subjects

Elias Tsakanikos

Publications and source records attributed to Elias Tsakanikos.

12 recordsLinked to original sources

PubMed2007

Disruption of synaesthesia following TMS of the right posterior parietal cortex.

This study examines the role of four regions of the parietal lobe in grapheme-colour synaesthesia. TMS applied over a right parieto-occipital region disrupts performance on a synaesthetic priming task. TMS over the left parietal or a more anterior right parietal site did not have a reliable effect on synaesthesia even though one of the sites had been implicated in synaesthesia by previous fMRI studies. The same disruption is found for synaesthetes who experience colours in their "mind's eye" as well as those who project colours onto the inducing grapheme. This region may be important for binding graphemes and colours to different spatial reference frames.

Adult↗

PubMed2007

Behaviour management problems as predictors of psychotropic medication and use of psychiatric services in adults with autism.

We examined behaviour management problems as predictors of psychotropic medication, use of psychiatric consultation and in-patient admission in a group of 66 adults with pervasive developmental disorder (PDD) and intellectual disability (ID) and 99 controls matched in age, gender and level of ID. Overall, people with PDD had higher rates of most DAS behaviour problems and more frequent use of anti-psychotics than matched controls. Logistic regression analyses showed that physical aggression and problems such as pestering staff independently predicted use of anti-psychotics. Physical aggression and overactivity predicted further involvement of psychiatric services. PDD diagnosis predicted admission to an in-patient unit. The results suggest that externalizing problem behaviours in adults with autism can predict type of treatment intervention.

Adult↗

PubMed2007

Referral trends in mental health services for adults with intellectual disability and autism spectrum disorders.

Researchers have paid increasing attention to mental health issues in adults with autism spectrum disorders (ASDs) over the last decades. However, little is known about how rates of clinical referrals, types of mental health diagnoses and treatment in adults with ASDs and intellectual disability have changed. We examined patterns of change in referral trends to specialist mental health services in south London from 1983 to 2000 (N = 137). The majority of the cases (58.4%) did not have a diagnosable psychiatric disorder. Schizophrenia was the most frequent psychiatric diagnosis followed by depression, adjustment reaction and anxiety. There was a significant change in the rate of referrals, an increase in the diagnosable psychiatric disorders over time and a significant reduction of medication at time of referral. There were no significant changes in the use of other therapeutic interventions. The proportion of participants living independently increased. Implications for services and future research are discussed.

Adult↗

PubMed2006

Multiple exposure to life events and clinical psychopathology in adults with intellectual disability.

BACKGROUND: Relatively few studies have examined the impact of life events on mental health in the field of intellectual disability (ID), despite the possibility that adults with ID and mental health problems might be particularly vulnerable to multiple events. AIMS: To examine the impact of multiple life events on mental health in people with ID. METHOD: The sample consisted of 281 men and women with ID consecutively referred to a specialist mental health service in South-East London. For each participant, key informants completed the PAS-ADD Life Events list, while psychiatric diagnoses were made by clinicians based on ICD-10 criteria. RESULTS: Logistic regression analysis revealed that single exposure to life events was significantly associated with female gender, schizophrenia, personality disorders and depression. However, multiple exposure to life events was associated with personality disorder, depression and adjustment reaction. CONCLUSIONS: The present results suggest an increased vulnerability to life events in people with ID. A better understanding of the relationship between life events and mental health can enhance the development of interventions, which may benefit substantially this particular population.

Adolescent↗

PubMed2006

Psychopathology in adults with autism and intellectual disability.

There have been few studies of psychopathology in adult with autism. This study examined psychiatric co-morbidity in 147 adults with intellectual disability (ID) and autism and 605 adults with ID but without autism. After controlling for the effects of gender, age, psychotropic medication and level of ID, people with autism and ID were no more likely to receive a psychiatric diagnosis than people with ID only. People with autism were less likely to receive a diagnosis of personality disorder. These findings cast doubts on the hypothesis that adults with ID and autism are more vulnerable to certain psychiatric disorders than non-autistic adults with ID.

Adolescent↗

PubMed2006

Sound-colour synaesthesia: to what extent does it use cross-modal mechanisms common to us all?

This study examines a group of synaesthetes who report colour sensations in response to music and other sounds. Experiment 1 shows that synaesthetes choose more precise colours and are more internally consistent in their choice of colours given a set of sounds of varying pitch, timbre and composition (single notes or dyads) relative to a group of controls. In spite of this difference, both controls and synaesthetes appear to use the same heuristics for matching between auditory and visual domains (e.g., pitch to lightness). We take this as evidence that synaesthesia may recruit some of the mechanisms used in normal cross-modal perception. Experiment 2 establishes that synaesthetic colours are automatically elicited insofar as they give rise to cross-modal Stroop interference. Experiment 3 uses a variant of the cross-modal Posner paradigm in which detection of a lateralised target is enhanced when combined with a non-informative but synaesthetically congruent sound-colour pairing. This suggests that synaesthesia uses the same (or an analogous) mechanism of exogenous cross-modal orienting as normal perception. Overall, the results support the conclusion that this form of synaesthesia recruits some of the same mechanisms used in normal cross-modal perception rather than using direct, privileged pathways between unimodal auditory and unimodal visual areas that are absent in most other adults.

Adult↗

PubMed2006

Synaesthesia: the prevalence of atypical cross-modal experiences.

Sensory and cognitive mechanisms allow stimuli to be perceived with properties relating to sight, sound, touch, etc, and ensure, for example, that visual properties are perceived as visual experiences, rather than sounds, tastes, smells, etc. Theories of normal development can be informed by cases where this modularity breaks down, in a condition known as synaesthesia. Conventional wisdom has held that this occurs extremely rarely (0.05% of births) and affects women more than men. Here we present the first test of synaesthesia prevalence with sampling that does not rely on self-referral, and which uses objective tests to establish genuineness. We show that (a) the prevalence of synaesthesia is 88 times higher than previously assumed, (b) the most common variant is coloured days, (c) the most studied variant (grapheme-colour synaesthesia)--previously believed most common--is prevalent at 1%, and (d) there is no strong asymmetry in the distribution of synaesthesia across the sexes. Hence, we suggest that female biases reported earlier likely arose from (or were exaggerated by) sex differences in self-disclosure.

Adult↗

PubMed2006

Synaesthesia for reading and playing musical notes.

This study reports three cases of synaesthesia who experience colors in response to written musical notation, graphemes and heard music. The synaesthetes show Stroop-like interference when asked to name the colour of graphemes but not for written musical notes. However, reliable interference is found in two further studies that require deeper processing of the musical notation (namely playing music from colored notation, and naming the synaesthetic color of the notes whilst suppressing the veridical color). This is the first empirical demonstration of synaesthesia for musical notation. The fact that synaesthetic color influences music playing/reading (a sensory-motor transformation) but not verbal color naming suggests that synaesthetic Stroop effects can arise from processing the meaning of a stimulus and not just as a result of verbal response interference. However, it is likely that the color associations themselves have a developmental origin in the names assigned to them. In all three cases, the colors of the written notes are related to the graphemes that arbitrarily denote them (e.g., 'A' may be "red" both as a letter and when written in musical notation). The results suggest that synaesthetic associations may migrate from one representational format (e.g., graphemes) to another (e.g., musical notation).

Acoustic Stimulation↗

PubMed2005

Do positive schizotypal symptoms predict false perceptual experiences in nonclinical populations?

We examined whether positive schizotypy (i.e., reports of hallucinatory and delusional-like experiences) in nonclinical participants could predict false perceptual experiences during detection of fast-moving words beyond a possible response bias. The participants (N = 160) were assigned to one of two conditions: they were asked either to make presence/absence judgments (loose criterion) or to read aloud every detected word (strict criterion). Regression analysis showed that high levels of positive schizotypy predicted false alarms in the loose condition and false perceptions of words in the strict condition. The obtained effects were independent of detection accuracy, task order, impulsivity, and social desirability. We discuss the results in the context of information processing biases linked to the positive symptomatology of schizophrenia. Clinical and theoretical implications are also considered.

Adolescent↗

PubMed2005

Seeing words that are not there: detection biases in schizotypy.

OBJECTIVE: The present study introduced a novel word-detection paradigm to examine detection biases as a function of different schizotypy dimensions in a sample of undergraduate students. METHOD: The participants (N = 80) were asked to detect fast moving (8 frames/second) words among simultaneously moving non-words. RESULTS: Positive schizotypy was associated with a tendency to report words that never appeared in the trials. This effect was independent of task order, impulsivity and social desirability. None of the schizotypy measures were associated with correct words (detection accuracy). CONCLUSIONS: A bias to report events in the absence of corresponding events may constitute a cross-modal mechanism responsible for translating internally generated experiences into perceptual experiences.

Adolescent↗

PubMed2004

Dimensional approaches to experimental psychopathology of schizophrenia: shift learning and report of psychotic-like experiences in college students.

Adopting a dimensional approach to experimental psychopathology, and taking into account inconsistencies in the previous literature, we examined whether reports of psychotic-like experiences in undergraduate students were associated with shift-learning deficits, akin to those seen in schizophrenia. The participants (N=72) were tested on a new compound stimulus discrimination task before and after a target shift, and were administered a multi-dimensional schizotypy inventory (O-LIFE). Performance impairment following a target shift was associated with the negative (introvertive anhedonia) and the impulsive (impulsive non-conformity) dimension of schizotypy, but not with the positive (unusual experiences), nor the disorganised (cognitive disorganisation) dimension. None of the schizotypy measures were associated with performance on discrimination learning before the target shift. The obtained results are in line with past evidence that shift learning is associated with the severity of the negative symptomatology of schizophrenia. The possibility that psychotic-like features may contribute differentially to performance deficits across successive stages of learning is considered.

Adolescent↗

PubMed2002

The influence of a distractor during compound preexposure on latent inhibition.

Nonreinforced exposure to a nontarget stimulus that was followed by nonreinforced exposure to a target/nontarget simultaneous compound stimulus resulted in enhanced latent inhibition of the target. Conditioning was slower after this treatment than after nonreinforced exposure to the target stimulus alone (Experiment 1). However, a salient auditory stimulus presented immediately after the compound in the second phase reduced levels of latent inhibition, relative to the enhanced latent inhibition produced when no such extracompound stimulus was presented (Experiments 2 and 3). This effect was not noted if the salient auditory cue was presented 10 sec after the termination of the compound stimulus (Experiment 4). In Experiment 5, there was no disruption of simple latent inhibition produced by a salient stimulus. These results are consistent with enhanced latent inhibition's being produced by the formation of within-compound associations, which are disrupted by the salient extracompound stimuli.

Animals↗